The invention is in the field of dental instruments, and particularly pertains to instruments for automatically making and recording periodontal pocket depth and attachment level measurements.
In the article entitled "The Accuracy of Clinical Parameters in Detecting Periodontal Disease Activity," by R. J. Ryan, Vol. III, J.A.D.A., November 1985, the vital importance of periodontal probing measurements in the early detection and diagnosis of periodontal disease is clearly laid out. Of particular importance are the measurements of gingival ("gum") pocket depths and periodontal attachment levels. In this regard, a periodontal pocket is a recess formed between a tooth and adjacent gum tissue or bone as a result of disease activity such as periodontitis. The depth of the pocket is indicative of the progress and severity of the disease process. The periodontal attachment level is the distance from the incisal or occlusal edge of the crown or the cemento enamel junction of the tooth to the depth of the periodontal pocket. The gingival level is the distance from the edge of the crown or the cemento enamel junction to the top of the gum margin. As is known, periodontal disease activity can cause loss of the anchoring jaw bone. The progress of periodontitis can be determined by measuring attachment levels from which assessment of periodontal bone loss can be determined.
Typically, dynamic disease activity can be determined by accumulating, over time, a set of measurements of pocket depths, gingival levels, and attachment levels and comparing them with corresponding currently-measured depths. In fact, periodic measurements are recommended in order to provide early detection of periodontal disease and to track its progress, once detected.
It is vital that each set of measurements include measurements of both pocket depth and periodontal attachment level. If only periodontal pocket depth is measured and recorded, the extent and level of periodontal bone destruction and disease activity may be missed.
Traditionally, depth and level measurements have been taken manually, with a periodontal practitioner obtaining them visually from a probe tip with calibrated markings.
U.S. Pat No. 3,058,225 of Ward illustrates an instrument for automatically obtaining a measurement of attachment level by means of a probe with a fixed sheath which engages the crown of a tooth when a measurement is made. A slidable needle is moved through the sheath into the periodontal pocket, and the distance between the tip of the needle and the end of the sheath is essentially the periodontal attachment level. In U.S. Pat. No. 3,943,914 of Grenfell et al, a periodontal probe with a stationary needle measures pocket depth by a sheath which slides on the needle to the edge of the gingival margin of the pocket when the needle's tip engages the bottom of the pocket. The distance between the end of the sheath and the tip of the needle is converted into an indication of the depth of the periodontal pocket. Neither of these references provides guidance for determining both the periodontal pocket depth and periodontal attachment level simultaneously in a single measurement.
When considering the construction of a historical record comprising a series of periodically-made periodontal measurements, the Grenfell patent provides a system for converting the gingival pocket depth measurements into printed numerical representations. In this system, archiving evidently consists of accumulating and storing printed representations made at different times. It is assumed that these measurements are manually transcribed onto a dental chart. The detection of change in measurements, which is the best indication of disease activity, thus depends upon visual interpretation of the printed measurement record, and manual transcription of the results into chart form.
The need, summarized in the cited Ryan article, for periodic measurement of both pocket depth and attachment level in a form which accommodates the differential comparison of sets of periodically-obtained measurements is therefore not adequately met by any system known to the Applicants.